/*#include "Platform.h"
#include "avsmallft.h"*/
using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Runtime.InteropServices;

namespace Droplet
{
    public class Smallft
    {
        public static void drfti1(int n,float[] wa,int[] ifac)
        {
            int[] ntryh = new int[4]{4,2,3,5};
            const float tpi = 6.28318530717958648f;
            float arg,argh,argld,fi;
            int ntry=0,i,j=-1;
            int k1, l1, l2, ib;
            int ld, ii, ip, m_is, nq, nr;
            int ido, ipm, nfm1;
            int nl=n;
            int nf=0;
        L101:
            j++;
            if (j < 4)
                ntry=ntryh[j];
            else
                ntry+=2;
        L104:
            nq=nl/ntry;
            nr=nl-ntry*nq;
            if (nr!=0) goto L101;
                nf++;
            ifac[nf+1]=ntry;
            nl=nq;
            if(ntry!=2)goto L107;
            if(nf==1)goto L107;
            for (i=1;i<nf;i++)
            {
                ib=nf-i+1;
                ifac[ib+1]=ifac[ib];
            }
            ifac[2] = 2;
        L107:
            if(nl!=1)goto L104;
            ifac[0]=n;
            ifac[1]=nf;
            argh=tpi/n;
            m_is=0;
            nfm1=nf-1;
            l1=1;
            if(nfm1==0)return;
            for (k1=0;k1<nfm1;k1++)
            {
                ip=ifac[k1+2];
                ld=0;
                l2=l1*ip;
                ido=n/l2;
                ipm=ip-1;
                for (j=0;j<ipm;j++)
                {
                    ld += l1;
                    i = m_is;
                    argld = (float)ld*argh;
                    fi = 0.0F;
                    for (ii=2;ii<ido;ii+=2)
                    {
                        fi += 1.0F;
                        arg = fi*argld;
                        wa[i++] = (float)Math.Cos(arg);
                        wa[i++] = (float)Math.Sin(arg);
                    }
                    m_is+=ido;
                }
                l1=l2;
                }
            }
            public static void fdrffti(int n,float[] wsave,int[] ifac)
            {
                if (n == 1) return;
                drfti1(n, arr_copy1(wsave, n), ifac);  //wsave+n
            }
            public static void dradf2(int ido,int l1,float[] cc,float[] ch,float[] wa1)
            {
                int i,k;
                float ti2,tr2;
                int t0,t1,t2,t3,t4,t5,t6;

                t1=0;
                t0=(t2=l1*ido);
                t3=ido<<1;
                for(k=0;k<l1;k++)
                {
                    ch[t1<<1]=cc[t1]+cc[t2];
                    ch[(t1<<1)+t3-1]=cc[t1]-cc[t2];
                    t1+=ido;
                    t2+=ido;
                }

                if(ido<2)return;
                if(ido==2)goto L105;

                t1=0;
                t2=t0;
                for(k=0;k<l1;k++)
                {
                    t3=t2;
                    t4=(t1<<1)+(ido<<1);
                    t5=t1;
                    t6=t1+t1;
                    for(i=2;i<ido;i+=2)
                    {
                        t3+=2;
                        t4-=2;
                        t5+=2;
                        t6+=2;
                        tr2=wa1[i-2]*cc[t3-1]+wa1[i-1]*cc[t3];
                        ti2=wa1[i-2]*cc[t3]-wa1[i-1]*cc[t3-1];
                        ch[t6]=cc[t5]+ti2;
                        ch[t4]=ti2-cc[t5];
                        ch[t6-1]=cc[t5-1]+tr2;
                        ch[t4-1]=cc[t5-1]-tr2;
                    }
                    t1+=ido;
                    t2+=ido;
                }
                if(ido%2==1)return;
            L105:
                t3=(t2=(t1=ido)-1);
                t2+=t0;
                for(k=0;k<l1;k++)
                {
                    ch[t1]=-cc[t2];
                    ch[t1-1]=cc[t3];
                    t1+=ido<<1;
                    t2+=ido;
                    t3+=ido;
                }
            }
            public static void dradf4(int ido,int l1,float[] cc,float[] ch,float[] wa1,float[] wa2,float[] wa3)
            {
                const float hsqt2 = .70710678118654752F;
                int i,k,t0,t1,t2,t3,t4,t5,t6;
                float ci2,ci3,ci4,cr2,cr3,cr4,ti1,ti2,ti3,ti4,tr1,tr2,tr3,tr4;
                t0=l1*ido;
              
                t1=t0;
                t4=t1<<1;
                t2=t1+(t1<<1);
                t3=0;

                for(k=0;k<l1;k++)
                {
                    tr1=cc[t1]+cc[t2];
                    tr2=cc[t3]+cc[t4];

                    ch[t5=t3<<2]=tr1+tr2;
                    ch[(ido<<2)+t5-1]=tr2-tr1;
                    ch[(t5+=(ido<<1))-1]=cc[t3]-cc[t4];
                    ch[t5]=cc[t2]-cc[t1];

                    t1+=ido;
                    t2+=ido;
                    t3+=ido;
                    t4+=ido;
                }

                if(ido<2)return;
                if(ido==2)goto L105;

                t1=0;
                for(k=0;k<l1;k++)
                {
                    t2=t1;
                    t4=t1<<2;
                    t5=(t6=ido<<1)+t4;
                    for(i=2;i<ido;i+=2)
                    {
                        t3=(t2+=2);
                        t4+=2;
                        t5-=2;

                        t3+=t0;
                        cr2=wa1[i-2]*cc[t3-1]+wa1[i-1]*cc[t3];
                        ci2=wa1[i-2]*cc[t3]-wa1[i-1]*cc[t3-1];
                        t3+=t0;
                        cr3=wa2[i-2]*cc[t3-1]+wa2[i-1]*cc[t3];
                        ci3=wa2[i-2]*cc[t3]-wa2[i-1]*cc[t3-1];
                        t3+=t0;
                        cr4=wa3[i-2]*cc[t3-1]+wa3[i-1]*cc[t3];
                        ci4=wa3[i-2]*cc[t3]-wa3[i-1]*cc[t3-1];

                        tr1=cr2+cr4;
                        tr4=cr4-cr2;
                        ti1=ci2+ci4;
                        ti4=ci2-ci4;

                        ti2=cc[t2]+ci3;
                        ti3=cc[t2]-ci3;
                        tr2=cc[t2-1]+cr3;
                        tr3=cc[t2-1]-cr3;

                        ch[t4-1]=tr1+tr2;
                        ch[t4]=ti1+ti2;

                        ch[t5-1]=tr3-ti4;
                        ch[t5]=tr4-ti3;

                        ch[t4+t6-1]=ti4+tr3;
                        ch[t4+t6]=tr4+ti3;

                        ch[t5+t6-1]=tr2-tr1;
                        ch[t5+t6]=ti1-ti2;
                    }
                    t1+=ido;
                };
                if ((ido & 1) != 0) return;
             L105:
                t2=(t1=t0+ido-1)+(t0<<1);
                t3=ido<<2;
                t4=ido;
                t5=ido<<1;
                t6=ido;

                for(k=0;k<l1;k++)
                {
                    ti1=-hsqt2*(cc[t1]+cc[t2]);
                    tr1=hsqt2*(cc[t1]-cc[t2]);

                    ch[t4-1]=tr1+cc[t6-1];
                    ch[t4+t5-1]=cc[t6-1]-tr1;

                    ch[t4]=ti1-cc[t1+t0];
                    ch[t4+t5]=ti1+cc[t1+t0];

                    t1+=ido;
                    t2+=ido;
                    t4+=t3;
                    t6+=ido;
                }
            }
            public static void dradfg(int ido,int ip,int l1,int idl1,float[] cc,float[] c1,float[] c2,float[] ch,float[] ch2,float[] wa)
            {
                const float tpi=6.283185307179586f;
                int idij,ipph,i,j,k,l,ic,ik,m_is;
                int t0,t1,t2,t3,t4,t5,t6,t7,t8,t9,t10;
                float dc2,ai1,ai2,ar1,ar2,ds2;
                int nbd;
                float dcp,arg,dsp,ar1h,ar2h;
                int idp2,ipp2;

                arg =tpi/(float)ip;
                dcp = (float)Math.Cos(arg);
                dsp = (float)Math.Cos(arg);
                ipph = (ip+1)>>1;
                ipp2 = ip;
                idp2 = ido;
                nbd = (ido-1)>>1;
                t0  = l1*ido;
                t10 = ip*ido;

                if(ido == 1) goto L119;
                for(ik = 0; ik < idl1; ik++) ch2[ik]=c2[ik];

                t1=0;
                for(j=1;j<ip;j++)
                {
                    t1+=t0;
                    t2=t1;
                    for(k=0;k<l1;k++)
                    {
                        ch[t2]=c1[t2];
                        t2+=ido;
                    }
                }
                m_is=-ido;
                t1=0;
                if(nbd>l1)
                {
                    for(j=1;j<ip;j++)
                    {
                        t1+=t0;
                        m_is+=ido;
                        t2= -ido+t1;
                        for(k=0;k<l1;k++)
                        {
                            idij=m_is-1;
                            t2+=ido;
                            t3=t2;
                            for(i=2;i<ido;i+=2)
                            {
                                idij+=2;
                                t3+=2;
                                ch[t3-1]=wa[idij-1]*c1[t3-1]+wa[idij]*c1[t3];
                                ch[t3]=wa[idij-1]*c1[t3]-wa[idij]*c1[t3-1];
                            }
                        }
                    }
                }
                else
                {
                    for(j=1;j<ip;j++)
                    {
                        m_is+=ido;
                        idij=m_is-1;
                        t1+=t0;
                        t2=t1;
                        for(i=2;i<ido;i+=2)
                        {
                            idij+=2;
                            t2+=2;
                            t3=t2;
                            for(k=0;k<l1;k++)
                            {
                                ch[t3-1]=wa[idij-1]*c1[t3-1]+wa[idij]*c1[t3];
                                ch[t3]=wa[idij-1]*c1[t3]-wa[idij]*c1[t3-1];
                                t3+=ido;
                            }
                        }
                    }
                }
                t1=0;
                t2=ipp2*t0;
                if(nbd<l1)
                {
                    for(j=1;j<ipph;j++)
                    {
                        t1+=t0;
                        t2-=t0;
                        t3=t1;
                        t4=t2;
                        for(i=2;i<ido;i+=2)
                        {
                            t3+=2;
                            t4+=2;
                            t5=t3-ido;
                            t6=t4-ido;
                            for(k=0;k<l1;k++)
                            {
                                t5+=ido;
                                t6+=ido;
                                c1[t5-1]=ch[t5-1]+ch[t6-1];
                                c1[t6-1]=ch[t5]-ch[t6];
                                c1[t5]=ch[t5]+ch[t6];
                                c1[t6]=ch[t6-1]-ch[t5-1];
                            }
                        }
                    }
                }
                else
                {
                    for(j=1;j<ipph;j++)
                    {
                        t1+=t0;
                        t2-=t0;
                        t3=t1;
                        t4=t2;
                        for(k=0;k<l1;k++)
                        {
                            t5=t3;
                            t6=t4;
                            for(i=2;i<ido;i+=2)
                            {
                                t5+=2;
                                t6+=2;
                                c1[t5-1]=ch[t5-1]+ch[t6-1];
                                c1[t6-1]=ch[t5]-ch[t6];
                                c1[t5]=ch[t5]+ch[t6];
                                c1[t6]=ch[t6-1]-ch[t5-1];
                            }
                            t3+=ido;
                            t4+=ido;
                        }
                    }
                }

            L119:
                for(ik=0;ik<idl1;ik++) c2[ik]=ch2[ik];

                t1=0;
                t2=ipp2*idl1;
                for(j=1;j<ipph;j++)
                {
                    t1+=t0;
                    t2-=t0;
                    t3=t1-ido;
                    t4=t2-ido;
                    for(k=0;k<l1;k++)
                    {
                        t3+=ido;
                        t4+=ido;
                        c1[t3]=ch[t3]+ch[t4];
                        c1[t4]=ch[t4]-ch[t3];
                    }
                }

                ar1=1.0F;
                ai1=0.0F;
                t1=0;
                t2=ipp2*idl1;
                t3=(ip-1)*idl1;
                for(l=1;l<ipph;l++)
                {
                    t1+=idl1;
                    t2-=idl1;
                    ar1h=dcp*ar1-dsp*ai1;
                    ai1=dcp*ai1+dsp*ar1;
                    ar1=ar1h;
                    t4=t1;
                    t5=t2;
                    t6=t3;
                    t7=idl1;

                    for(ik=0;ik<idl1;ik++)
                    {
                        ch2[t4++]=c2[ik]+ar1*c2[t7++];
                        ch2[t5++]=ai1*c2[t6++];
                    }

                    dc2=ar1;
                    ds2=ai1;
                    ar2=ar1;
                    ai2=ai1;

                    t4=idl1;
                    t5=(ipp2-1)*idl1;
                    for(j=2;j<ipph;j++)
                    {
                        t4+=idl1;
                        t5-=idl1;

                        ar2h=dc2*ar2-ds2*ai2;
                        ai2=dc2*ai2+ds2*ar2;
                        ar2=ar2h;

                        t6=t1;
                        t7=t2;
                        t8=t4;
                        t9=t5;
                        for(ik=0;ik<idl1;ik++)
                        {
                            ch2[t6++]+=ar2*c2[t8++];
                            ch2[t7++]+=ai2*c2[t9++];
                        }
                    }
                }

                t1=0;
                for(j=1;j<ipph;j++)
                {
                    t1+=idl1;
                    t2=t1;
                    for(ik=0;ik<idl1;ik++)ch2[ik]+=c2[t2++];
                }

                if(ido<l1)goto L132;

                t1=0;
                t2=0;
                for(k=0;k<l1;k++)
                {
                    t3=t1;
                    t4=t2;
                    for(i=0;i<ido;i++)cc[t4++]=ch[t3++];
                    t1+=ido;
                    t2+=t10;
                }
                goto L135;
            L132:
                for(i=0;i<ido;i++)
                {
                    t1=i;
                    t2=i;
                    for(k=0;k<l1;k++)
                    {
                        cc[t2]=ch[t1];
                        t1+=ido;
                        t2+=t10;
                    }
                }

            L135:
                t1=0;
                t2=ido<<1;
                t3=0;
                t4=ipp2*t0;
                for(j=1;j<ipph;j++)
                {
                    t1+=t2;
                    t3+=t0;
                    t4-=t0;

                    t5=t1;
                    t6=t3;
                    t7=t4;

                    for(k=0;k<l1;k++)
                    {
                        cc[t5-1]=ch[t6];
                        cc[t5]=ch[t7];
                        t5+=t10;
                        t6+=ido;
                        t7+=ido;
                    }
                }

                if(ido==1)return;
                if(nbd<l1)goto L141;

                t1=-ido;
                t3=0;
                t4=0;
                t5=ipp2*t0;
                for(j=1;j<ipph;j++)
                {
                    t1+=t2;
                    t3+=t2;
                    t4+=t0;
                    t5-=t0;
                    t6=t1;
                    t7=t3;
                    t8=t4;
                    t9=t5;
                    for(k=0;k<l1;k++)
                    {
                        for(i=2;i<ido;i+=2)
                        {
                            ic=idp2-i;
                            cc[i+t7-1]=ch[i+t8-1]+ch[i+t9-1];
                            cc[ic+t6-1]=ch[i+t8-1]-ch[i+t9-1];
                            cc[i+t7]=ch[i+t8]+ch[i+t9];
                            cc[ic+t6]=ch[i+t9]-ch[i+t8];
                        }
                        t6+=t10;
                        t7+=t10;
                        t8+=ido;
                        t9+=ido;
                    }
                }
                return;

            L141:
                t1=-ido;
                t3=0;
                t4=0;
                t5=ipp2*t0;
                for(j=1;j<ipph;j++)
                {
                    t1+=t2;
                    t3+=t2;
                    t4+=t0;
                    t5-=t0;
                    for(i=2;i<ido;i+=2)
                    {
                        t6=idp2+t1-i;
                        t7=i+t3;
                        t8=i+t4;
                        t9=i+t5;
                        for(k=0;k<l1;k++)
                        {
                            cc[t7-1]=ch[t8-1]+ch[t9-1];
                            cc[t6-1]=ch[t8-1]-ch[t9-1];
                            cc[t7]=ch[t8]+ch[t9];
                            cc[t6]=ch[t9]-ch[t8];
                            t6+=t10;
                            t7+=t10;
                            t8+=ido;
                            t9+=ido;
                        }
                    }
                }
            }
            public static void drftf1(int n,float[] c,float[] ch,float[] wa,int[] ifac)
            {
                int i,k1,l1,l2;
                int na,kh,nf;
                int ip,iw,ido,idl1,ix2,ix3;

                nf=ifac[1];
                na=1;
                l2=n;
                iw=n;

                for(k1=0;k1<nf;k1++)
                {
                    kh=nf-k1;
                    ip=ifac[kh+1];
                    l1=l2/ip;
                    ido=n/l2;
                    idl1=ido*l1;
                    iw-=(ip-1)*ido;
                    na=1-na;

                    if(ip!=4)goto L102;

                    ix2=iw+ido;
                    ix3=ix2+ido;
                    if (na != 0)            
                        dradf4(ido, l1, ch, c, arr_copy1(wa,iw-1), arr_copy1(wa,ix2-1), arr_copy1(wa,ix3-1));     //wa + iw - 1    wa + ix2 - 1   wa + ix3 - 1
                    else
                        dradf4(ido, l1, c, ch, arr_copy1(wa,iw-1), arr_copy1(wa,ix2-1), arr_copy1(wa,ix3-1));  //wa + iw - 1   wa + ix2 - 1  wa + ix3 - 1
                    goto L110;
            L102:
                    if(ip!=2)goto L104;
                    if(na!=0)goto L103;

                    dradf2(ido,l1,c,ch,arr_copy1(wa,iw-1));  //wa+iw-1
                    goto L110;
            L103:
                    dradf2(ido, l1, ch, c, arr_copy1(wa, iw - 1));  //wa+iw-1
                    goto L110;
            L104:
                    if(ido==1)na=1-na;
                    if(na!=0)goto L109;

                    dradfg(ido, ip, l1, idl1, c, c, c, ch, ch, arr_copy1(wa, iw - 1));  //wa+iw-1
                    na=1;
                    goto L110;
            L109:
                    dradfg(ido, ip, l1, idl1, ch, ch, ch, c, c, arr_copy1(wa, iw - 1));  //wa+iw-1
                    na=0;
            L110:
                    l2=l1;
                }
                if(na == 1) return;
                for(i = 0; i < n; i++) c[i] = ch[i];
            }
            public static void dradb2(int ido,int l1,float[] cc,float[] ch,float[] wa1)
            {
                int i,k,t0,t1,t2,t3,t4,t5,t6;
                float ti2,tr2;

                t0=l1*ido;

                t1=0;
                t2=0;
                t3=(ido<<1)-1;
                for(k=0;k<l1;k++)
                {
                    ch[t1]=cc[t2]+cc[t3+t2];
                    ch[t1+t0]=cc[t2]-cc[t3+t2];
                    t2=(t1+=ido)<<1;
                }

                if(ido<2)return;
                if(ido==2)goto L105;

                t1=0;
                t2=0;
                for(k=0;k<l1;k++)
                {
                    t3=t1;
                    t5=(t4=t2)+(ido<<1);
                    t6=t0+t1;
                    for(i=2;i<ido;i+=2)
                    {
                        t3+=2;
                        t4+=2;
                        t5-=2;
                        t6+=2;
                        ch[t3-1]=cc[t4-1]+cc[t5-1];
                        tr2=cc[t4-1]-cc[t5-1];
                        ch[t3]=cc[t4]-cc[t5];
                        ti2=cc[t4]+cc[t5];
                        ch[t6-1]=wa1[i-2]*tr2-wa1[i-1]*ti2;
                        ch[t6]=wa1[i-2]*ti2+wa1[i-1]*tr2;
                    }
                    t2=(t1+=ido)<<1;
                }

                if(ido%2==1)return;

            L105:
                t1=ido-1;
                t2=ido-1;
                for(k=0;k<l1;k++)
                {
                    ch[t1]=cc[t2]+cc[t2];
                    ch[t1+t0]=-(cc[t2+1]+cc[t2+1]);
                    t1+=ido;
                    t2+=ido<<1;
                }
            }
            public static void dradb3(int ido,int l1,float[] cc,float[] ch,float[] wa1,float[] wa2)
            {
                const float taur = -.5f;
                const float taui = .8660254037844386f;
                int i,k,t0,t1,t2,t3,t4,t5,t6,t7,t8,t9,t10;
                float ci2,ci3,di2,di3,cr2,cr3,dr2,dr3,ti2,tr2;
                t0=l1*ido;

                t1=0;
                t2=t0<<1;
                t3=ido<<1;
                t4=ido+(ido<<1);
                t5=0;
                for(k=0;k<l1;k++)
                {
                    tr2=cc[t3-1]+cc[t3-1];
                    cr2=cc[t5]+(taur*tr2);
                    ch[t1]=cc[t5]+tr2;
                    ci3=taui*(cc[t3]+cc[t3]);
                    ch[t1+t0]=cr2-ci3;
                    ch[t1+t2]=cr2+ci3;
                    t1+=ido;
                    t3+=t4;
                    t5+=t4;
                }

                if(ido==1)return;

                t1=0;
                t3=ido<<1;
                for(k=0;k<l1;k++)
                {
                    t7=t1+(t1<<1);
                    t6=(t5=t7+t3);
                    t8=t1;
                    t10=(t9=t1+t0)+t0;

                    for(i=2;i<ido;i+=2)
                    {
                        t5+=2;
                        t6-=2;
                        t7+=2;
                        t8+=2;
                        t9+=2;
                        t10+=2;
                        tr2=cc[t5-1]+cc[t6-1];
                        cr2=cc[t7-1]+(taur*tr2);
                        ch[t8-1]=cc[t7-1]+tr2;
                        ti2=cc[t5]-cc[t6];
                        ci2=cc[t7]+(taur*ti2);
                        ch[t8]=cc[t7]+ti2;
                        cr3=taui*(cc[t5-1]-cc[t6-1]);
                        ci3=taui*(cc[t5]+cc[t6]);
                        dr2=cr2-ci3;
                        dr3=cr2+ci3;
                        di2=ci2+cr3;
                        di3=ci2-cr3;
                        ch[t9-1]=wa1[i-2]*dr2-wa1[i-1]*di2;
                        ch[t9]=wa1[i-2]*di2+wa1[i-1]*dr2;
                        ch[t10-1]=wa2[i-2]*dr3-wa2[i-1]*di3;
                        ch[t10]=wa2[i-2]*di3+wa2[i-1]*dr3;
                    }
                    t1+=ido;
                }
            }
            public static void dradb4(int ido,int l1,float[] cc,float[] ch,float[] wa1,float[] wa2,float[] wa3)
            {
                const float sqrt2=1.414213562373095f;
                int i,k,t0,t1,t2,t3,t4,t5,t6,t7,t8;
                float ci2,ci3,ci4,cr2,cr3,cr4,ti1,ti2,ti3,ti4,tr1,tr2,tr3,tr4;
                t0=l1*ido;

                t1=0;
                t2=ido<<2;
                t3=0;
                t6=ido<<1;
                for(k = 0; k < l1; k++)
                {
                    t4=t3+t6;
                    t5=t1;
                    tr3=cc[t4-1]+cc[t4-1];
                    tr4=cc[t4]+cc[t4]; 
                    tr1=cc[t3]-cc[(t4+=t6)-1];
                    tr2=cc[t3]+cc[t4-1];
                    ch[t5]=tr2+tr3;
                    ch[t5+=t0]=tr1-tr4;
                    ch[t5+=t0]=tr2-tr3;
                    ch[t5+=t0]=tr1+tr4;
                    t1+=ido;
                    t3+=t2;
                }
                
                if(ido < 2) return;
                if(ido == 2) goto L105;

                t1=0;
                for(k=0;k<l1;k++)
                {
                    t5=(t4=(t3=(t2=t1<<2)+t6))+t6;
                    t7=t1;
                    for(i=2;i<ido;i+=2)
                    {
                        t2+=2;
                        t3+=2;
                        t4-=2;
                        t5-=2;
                        t7+=2;
                        ti1=cc[t2]+cc[t5];
                        ti2=cc[t2]-cc[t5];
                        ti3=cc[t3]-cc[t4];
                        tr4=cc[t3]+cc[t4];
                        tr1=cc[t2-1]-cc[t5-1];
                        tr2=cc[t2-1]+cc[t5-1];
                        ti4=cc[t3-1]-cc[t4-1];
                        tr3=cc[t3-1]+cc[t4-1];
                        ch[t7-1]=tr2+tr3;
                        cr3=tr2-tr3;
                        ch[t7]=ti2+ti3;
                        ci3=ti2-ti3;
                        cr2=tr1-tr4;
                        cr4=tr1+tr4;
                        ci2=ti1+ti4;
                        ci4=ti1-ti4;

                        ch[(t8=t7+t0)-1]=wa1[i-2]*cr2-wa1[i-1]*ci2;
                        ch[t8]=wa1[i-2]*ci2+wa1[i-1]*cr2;
                        ch[(t8+=t0)-1]=wa2[i-2]*cr3-wa2[i-1]*ci3;
                        ch[t8]=wa2[i-2]*ci3+wa2[i-1]*cr3;
                        ch[(t8+=t0)-1]=wa3[i-2]*cr4-wa3[i-1]*ci4;
                        ch[t8]=wa3[i-2]*ci4+wa3[i-1]*cr4;
                    }
                    t1+=ido;
                }
                if(ido%2 == 1)return;
            L105:
                t1=ido;
                t2=ido<<2;
                t3=ido-1;
                t4=ido+(ido<<1);
                for(k=0;k<l1;k++)
                {
                    t5=t3;
                    ti1=cc[t1]+cc[t4];
                    ti2=cc[t4]-cc[t1];
                    tr1=cc[t1-1]-cc[t4-1];
                    tr2=cc[t1-1]+cc[t4-1];
                    ch[t5]=tr2+tr2;
                    ch[t5+=t0]=sqrt2*(tr1-ti1);
                    ch[t5+=t0]=ti2+ti2;
                    ch[t5+=t0]=-sqrt2*(tr1+ti1);

                    t3+=ido;
                    t1+=t2;
                    t4+=t2;
                }
            }
            public static void dradbg(int ido,int ip,int l1,int idl1,float[] cc,float[] c1,float[] c2,float[] ch,float[] ch2,float[] wa)
            {
                const float tpi = 6.283185307179586f;
                int idij,ipph,i,j,k,l,ik,m_is,t0,t1,t2,t3,t4,t5,t6,t7,t8,t9,t10,t11,t12;
                float dc2,ai1,ai2,ar1,ar2,ds2;
                int nbd;
                float dcp,arg,dsp,ar1h,ar2h;
                int ipp2;

                t10 = ip*ido;
                t0 = l1*ido;
                arg = tpi/(float)ip;
                dcp = (float)Math.Cos(arg);
                dsp = (float)Math.Cos(arg);
                nbd = (ido-1)>>1;
                ipp2 = ip;
                ipph = (ip+1)>>1;
                if(ido < l1) goto L103;

                t1 = 0;
                t2 = 0;
                for(k = 0; k < l1; k++)
                {
                    t3=t1;
                    t4=t2;
                    for(i=0;i<ido;i++)
                    {
                        ch[t3]=cc[t4];
                        t3++;
                        t4++;
                    }
                    t1+=ido;
                    t2+=t10;
                }
                goto L106;

            L103:
                t1=0;
                for(i=0;i<ido;i++)
                {
                    t2=t1;
                    t3=t1;
                    for(k=0;k<l1;k++)
                    {
                        ch[t2]=cc[t3];
                        t2+=ido;
                        t3+=t10;
                    }
                    t1++;
                }

            L106:
                t1=0;
                t2=ipp2*t0;
                t7=(t5=ido<<1);
                for(j=1;j<ipph;j++)
                {
                    t1+=t0;
                    t2-=t0;
                    t3=t1;
                    t4=t2;
                    t6=t5;
                    for(k=0;k<l1;k++)
                    {
                        ch[t3]=cc[t6-1]+cc[t6-1];
                        ch[t4]=cc[t6]+cc[t6];
                        t3+=ido;
                        t4+=ido;
                        t6+=t10;
                    }
                    t5+=t7;
                }

                if (ido == 1)goto L116;
                if(nbd<l1)goto L112;

                t1=0;
                t2=ipp2*t0;
                t7=0;
                for(j=1;j<ipph;j++)
                {
                    t1+=t0;
                    t2-=t0;
                    t3=t1;
                    t4=t2;

                    t7+=(ido<<1);
                    t8=t7;
                    for(k=0;k<l1;k++)
                    {
                        t5=t3;
                        t6=t4;
                        t9=t8;
                        t11=t8;
                        for(i=2;i<ido;i+=2)
                        {
                            t5+=2;
                            t6+=2;
                            t9+=2;
                            t11-=2;
                            ch[t5-1]=cc[t9-1]+cc[t11-1];
                            ch[t6-1]=cc[t9-1]-cc[t11-1];
                            ch[t5]=cc[t9]-cc[t11];
                            ch[t6]=cc[t9]+cc[t11];
                        }
                        t3+=ido;
                        t4+=ido;
                        t8+=t10;
                    }
                }
                goto L116;

            L112:
                t1=0;
                t2=ipp2*t0;
                t7=0;
                for(j=1;j<ipph;j++)
                {
                    t1+=t0;
                    t2-=t0;
                    t3=t1;
                    t4=t2;
                    t7+=(ido<<1);
                    t8=t7;
                    t9=t7;
                    for(i=2;i<ido;i+=2)
                    {
                        t3+=2;
                        t4+=2;
                        t8+=2;
                        t9-=2;
                        t5=t3;
                        t6=t4;
                        t11=t8;
                        t12=t9;
                        for(k=0;k<l1;k++)
                        {
                            ch[t5-1]=cc[t11-1]+cc[t12-1];
                            ch[t6-1]=cc[t11-1]-cc[t12-1];
                            ch[t5]=cc[t11]-cc[t12];
                            ch[t6]=cc[t11]+cc[t12];
                            t5+=ido;
                            t6+=ido;
                            t11+=t10;
                            t12+=t10;
                        }
                    }
                }

            L116:
                ar1=1.0F;
                ai1=0.0F;
                t1=0;
                t9=(t2=ipp2*idl1);
                t3=(ip-1)*idl1;
                for(l=1;l<ipph;l++)
                {
                    t1+=idl1;
                    t2-=idl1;

                    ar1h=dcp*ar1-dsp*ai1;
                    ai1=dcp*ai1+dsp*ar1;
                    ar1=ar1h;
                    t4=t1;
                    t5=t2;
                    t6=0;
                    t7=idl1;
                    t8=t3;
                    for(ik=0;ik<idl1;ik++)
                    {
                        c2[t4++]=ch2[t6++]+ar1*ch2[t7++];
                        c2[t5++]=ai1*ch2[t8++];
                    }
                    dc2=ar1;
                    ds2=ai1;
                    ar2=ar1;
                    ai2=ai1;

                    t6=idl1;
                    t7=t9-idl1;
                    for(j=2;j<ipph;j++)
                    {
                        t6+=idl1;
                        t7-=idl1;
                        ar2h=dc2*ar2-ds2*ai2;
                        ai2=dc2*ai2+ds2*ar2;
                        ar2=ar2h;
                        t4=t1;
                        t5=t2;
                        t11=t6;
                        t12=t7;
                        for(ik=0;ik<idl1;ik++)
                        {
                            c2[t4++]+=ar2*ch2[t11++];
                            c2[t5++]+=ai2*ch2[t12++];
                        }
                    }
                }

                t1=0;
                for(j=1;j<ipph;j++)
                {
                    t1+=idl1;
                    t2=t1;
                    for(ik=0;ik<idl1;ik++)ch2[ik]+=ch2[t2++];
                }

                t1=0;
                t2=ipp2*t0;
                for(j=1;j<ipph;j++)
                {
                    t1+=t0;
                    t2-=t0;
                    t3=t1;
                    t4=t2;
                    for(k=0;k<l1;k++)
                    {
                        ch[t3]=c1[t3]-c1[t4];
                        ch[t4]=c1[t3]+c1[t4];
                        t3+=ido;
                        t4+=ido;
                    }
                }

                if(ido==1)goto L132;
                if(nbd<l1)goto L128;

                t1=0;
                t2=ipp2*t0;
                for(j=1;j<ipph;j++)
                {
                    t1+=t0;
                    t2-=t0;
                    t3=t1;
                    t4=t2;
                    for(k=0;k<l1;k++)
                    {
                        t5=t3;
                        t6=t4;
                        for(i=2;i<ido;i+=2)
                        {
                            t5+=2;
                            t6+=2;
                            ch[t5-1]=c1[t5-1]-c1[t6];
                            ch[t6-1]=c1[t5-1]+c1[t6];
                            ch[t5]=c1[t5]+c1[t6-1];
                            ch[t6]=c1[t5]-c1[t6-1];
                        }
                        t3+=ido;
                        t4+=ido;
                    }
                }
                goto L132;

            L128:
                t1=0;
                t2=ipp2*t0;
                for(j=1;j<ipph;j++)
                {
                    t1+=t0;
                    t2-=t0;
                    t3=t1;
                    t4=t2;
                    for(i=2;i<ido;i+=2)
                    {
                        t3+=2;
                        t4+=2;
                        t5=t3;
                        t6=t4;
                        for(k=0;k<l1;k++)
                        {
                            ch[t5-1]=c1[t5-1]-c1[t6];
                            ch[t6-1]=c1[t5-1]+c1[t6];
                            ch[t5]=c1[t5]+c1[t6-1];
                            ch[t6]=c1[t5]-c1[t6-1];
                            t5+=ido;
                            t6+=ido;
                        }
                    }
                }

            L132:
                if(ido==1)return;

                for(ik=0;ik<idl1;ik++)c2[ik]=ch2[ik];

                t1=0;
                for(j=1;j<ip;j++)
                {
                    t2=(t1+=t0);
                    for(k=0;k<l1;k++)
                    {
                        c1[t2]=ch[t2];
                        t2+=ido;
                    }
                }

                if(nbd>l1)goto L139;

                m_is= -ido-1;
                t1=0;
                for(j=1;j<ip;j++)
                {
                    m_is+=ido;
                    t1+=t0;
                    idij=m_is;
                    t2=t1;
                    for(i=2;i<ido;i+=2)
                    {
                        t2+=2;
                        idij+=2;
                        t3=t2;
                        for(k=0;k<l1;k++)
                        {
                            c1[t3-1]=wa[idij-1]*ch[t3-1]-wa[idij]*ch[t3];
                            c1[t3]=wa[idij-1]*ch[t3]+wa[idij]*ch[t3-1];
                            t3+=ido;
                        }
                    }
                }
                return;

            L139:
                m_is= -ido-1;
                t1=0;
                for(j=1;j<ip;j++)
                {
                    m_is+=ido;
                    t1+=t0;
                    t2=t1;
                    for(k=0;k<l1;k++)
                    {
                        idij=m_is;
                        t3=t2;
                        for(i=2;i<ido;i+=2)
                        {
                            idij+=2;
                            t3+=2;
                            c1[t3-1]=wa[idij-1]*ch[t3-1]-wa[idij]*ch[t3];
                            c1[t3]=wa[idij-1]*ch[t3]+wa[idij]*ch[t3-1];
                        }
                        t2+=ido;
                    }
                }
            }
            public static void drftb1(int n,float[] c,float[] ch,float[] wa,int[] ifac)
            {
                int i,k1,l1,l2;
                int na;
                int nf,ip,iw,ix2,ix3,ido,idl1;

                nf  = ifac[1];
                na  = 0;
                l1  = 1;
                iw  = 1;

                for(k1=0;k1<nf;k1++)
                {
                    ip = ifac[k1 + 2];
                    l2 = ip*l1;
                    ido = n/l2;
                    idl1= ido*l1;
                    if(ip != 4) goto L103;
                    ix2 = iw+ido;
                    ix3 = ix2+ido;

                    if(na != 0)
                        dradb4(ido,l1,ch,c,arr_copy1(wa,iw-1),arr_copy1(wa,ix2-1),arr_copy1(wa,ix3-1));  //wa+iw-1  wa+ix2-1  wa+ix3-1
                    else
                        dradb4(ido,l1,c,ch,arr_copy1(wa,iw-1),arr_copy1(wa,ix2-1),arr_copy1(wa,ix3-1));  //wa+iw-1  wa+ix2-1  wa+ix3-1
                    na = 1-na;
                    goto L115;
            L103:
                    if(ip!=2) goto L106;
                    if(na!=0)
                        dradb2(ido,l1,ch,c,arr_copy1(wa,iw-1));  //wa+iw-1
                    else
                        dradb2(ido, l1, c, ch, arr_copy1(wa, iw - 1));  //wa+iw-1
                    na = 1-na;
                    goto L115;
            L106:
                    if(ip != 3) goto L109;
                    ix2 = iw+ido;
                    if(na != 0)
                        dradb3(ido,l1,ch,c,arr_copy1(wa,iw-1),arr_copy1(wa,ix2-1));  //wa+iw-1 wa+ix2-1
                    else
                        dradb3(ido,l1,c,ch,arr_copy1(wa,iw-1),arr_copy1(wa,ix2-1));  //wa+iw-1  wa+ix2-1
                    na = 1-na;
                    goto L115;
            L109:
                    if(na != 0)
                        dradbg(ido,ip,l1,idl1,ch,ch,ch,c,c,arr_copy1(wa,iw-1));  //wa+iw-1
                    else
                        dradbg(ido, ip, l1, idl1, c, c, c, ch, ch, arr_copy1(wa, iw - 1));  ////wa+iw-1
                    if(ido == 1) na = 1-na;
            L115:
                    l1 = l2;
                    iw += (ip-1)*ido;
                }
                if(na == 0) return;
                for(i = 0; i < n; i++) c[i] = ch[i];
            }
            public static void spx_drft_forward(drft_lookup[] l,float[] data)
            {
                if (drft_lookup.n == 1) return;
                drftf1(drft_lookup.n, data, drft_lookup.trigcache, arr_copy1(drft_lookup.trigcache, drft_lookup.n), drft_lookup.splitcache);  //drft_lookup.trigcache + drft_lookup.n
            }

            public static void spx_drft_backward(drft_lookup[] l,float[] data)
            {
                if (drft_lookup.n == 1) return;
                drftb1(drft_lookup.n, data, drft_lookup.trigcache, arr_copy1(drft_lookup.trigcache, drft_lookup.n), drft_lookup.splitcache);   //drft_lookup.trigcache + drft_lookup.n
            }

            public static void spx_drft_init(drft_lookup[] l,int n)
            {
                drft_lookup.n = n;
                //drft_lookup.trigcache = new float[3 * n * Marshal.SizeOf(drft_lookup.trigcache)];//(float[])calloc(3 * n * sizeof(drft_lookup.trigcache), 1);
                drft_lookup.trigcache = new float[3 * n * 1];
               // drft_lookup.splitcache = new int[32 * Marshal.SizeOf(drft_lookup.splitcache)];//(int[])calloc(32 * sizeof(drft_lookup.splitcache), 1);
              //  drft_lookup.splitcache = new int[32 * drft_lookup.splitcache.Length];
                drft_lookup.splitcache = new int[32 * 1];
                fdrffti(n, drft_lookup.trigcache, drft_lookup.splitcache);
            }

            public static void spx_drft_clear(drft_lookup[] l)
            {
                if (l != null)
                {
                    if (drft_lookup.trigcache != null)
                        //  free(l->trigcache);
                        drft_lookup.trigcache = null;
                    if (drft_lookup.splitcache != null)
                       // free(l->splitcache);
                        drft_lookup.splitcache = null;
                }
            }
            public static float[] arr_copy1(float[] arr,int n)
            {
                float[] temp;
                int len = arr.Length;
                temp = new float[len - n];
              //  arr.CopyTo(temp, n);
                Array.Copy(arr, n, temp, 0, len - n);
                return temp;
            }
        }
}





















